I'd really like to see also this become a feature, as well as changing the transparency of the pie charts and possibility to add an attribute as a label at the bottom or top of the Chart

ArcGIS Ideas posted by Aileen Buckley on Feb 3 2015 8:47AM

Best thing to do is to post your request or vote on it if someone has already submitted it on the ArcGIS Ideas page -- these suggestions have the attention of our software developers! http://ideas.arcgis.com/